Recent advances in the size and performance of micro-electromechanical systems (MEMS)-based inertial instruments enable the development of a novel balance prosthesis to provide feedback via a substitute sensory channel regarding head orientation to patients with chronic balance dysfunction. There is a need for balance prostheses to assist patients with chronic balance disorders, as well as for devices to facilitate rehabilitaton of such disorders through training and physical therapy. The noninvasive, discreet, turnkey BALCAP prosthesis proposed herein offers the potential to satisfy both requirements in a practicable and ergonomic fashion. The BALCAP prosthesis uses six degrees-of-freedom (6- DOF) sensing to detect postural imbalance and actuate low-amplitude vibrotactile cues directly to the head via hatband tactors that provide the wearer with feedback concerning head tilt in the pitch and roll planes (and combinations thereof). The BALCAP is designed to function correctly whether or not the participant is stationary or moving. The Phase I effort demonstrated initial feasibility for both the assistive and rehabilitative benefits of the BALCAP prosthesis. As part of the proposed research, the utility of an improved BALCAP balance prosthesis will be further evaluated in an expanded study on individuals with chronic balance dysfunction spanning a range of etiologies. Participants will undergo postural stability and gait assessments to evaluate two distinct hypotheses: (1) that performance scores improve significantly while wearing the BALCAP balance prosthesis (assistive benefit) and; (2) that performance scores improve after a period of BALCAP-assisted therapy vs. standard therapy, even when the BALCAP is not being worn (rehabilitative benefit). A head-mounted vibrotactile prosthesis, such as the proposed BALCAP, will provide immediate benefit to a large number of patients with chronic postural instability. Additionally, the device has the potential to open new areas of research, such as determining the optimal training protocol to maximize residual retention of balance improvements. The availability of a practical, one-piece, noninvasive, discreet, and low-cost balance prosthesis will enhance the quality of life for balance-disordered patients and could lead to further advancements in this area.